Hi!I designed custom board based on ESP8266EX and W25Q32.ESP8266EX drives by another MCU that is responsible for boot mode selection for ESP8266EX.Hardware setup to put ESP8266EX to boot mode via UART:VCC = 3V.GPIO15 (MTDO) connected directly to the GND all time.

Procedure of flashing is following:1. RESET pin to low2. GPIO2 to high3. GPIO0 to low4. CH_EN to high5. RESET pin to highThat pins drives another MCU.

The problem is that I can flash only 2 of 5 boards.I checked voltage levels on all pins using oscilloscope and they all in expected stateexcluding GPIO0 which is oscillating continously.

What can be an issue of that?Does oscillating means that ESP8266EX IC is alive?Does it can help to flash W25Q32 flash memory IC directly using FlashCAT SPI programmer?

Yes, 40MHz out should mean that there is a high likelihood that the ESP8266 is fine. Are you sure you soldered the chip correctly?Also, I cannot help without taking a look at the boot log.When you put ESP into programming mode, it will output something on UART at 74880 bauds. I will need to see that to help.

almaz1c wrote:Hi!I designed custom board based on ESP8266EX and W25Q32.ESP8266EX drives by another MCU that is responsible for boot mode selection for ESP8266EX.Hardware setup to put ESP8266EX to boot mode via UART:VCC = 3V.GPIO15 (MTDO) connected directly to the GND all time.

Procedure of flashing is following:1. RESET pin to low2. GPIO2 to high3. GPIO0 to low4. CH_EN to high5. RESET pin to highThat pins drives another MCU.

The problem is that I can flash only 2 of 5 boards.I checked voltage levels on all pins using oscilloscope and they all in expected stateexcluding GPIO0 which is oscillating continously.

What can be an issue of that?Does oscillating means that ESP8266EX IC is alive?Does it can help to flash W25Q32 flash memory IC directly using FlashCAT SPI programmer?

Hi,

it seems that your bootup sequence for burning is OK. But experiences tell us that the GPOIO had better be kept stable low during burning even though that it is theoratically to be low only neccessary upon reset exit and don't care after reset, since the on-chip bootup code might need time to sample the pin so that to enter boot-from-uart mode for burning. Meanwhile, the nRESET might goes high unexpected if the GPIO0 is not stable. I suggest you ties the GPIO0 to GND always and then have a try.

Secondly, if you can, you may please also try to slow down the uart speed when you burn.

Meanwhile, we have one-press burning tools for ESP8266 modules which is very helpful for batch burning. With the burning tool, you only have to have one press on the button of the software to start the burning, and then the burning process will be completed automatically with the help of UART flow control. If you feel interested, you may please get more about it at http://www.ebay.com/itm/282286419729. It is ready with pin connectors for ESP-01, ESP-12 etc. If your module does not have a matched connector here, you may please using 5 flying wires connecting to a connector which is matched with the connector on your module.

What is second digit y in "boot mode" ?I am able to get correct x digit in (x,y)I added capacitor to NRST pin. Replaced flash IC to new empty IC.Now when I try flash it using UART boot mode I get following:

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Espressif Systems is a fabless semiconductor company providing cutting-edge low power WiFi SoCs and wireless solutions for wireless communications and Internet of Things applications. We are the manufacturer of ESP8266EX.